1. Field of the Invention
The present invention relates to a cable connector for fastening a cable to a metal box and, more particularly, to such a cable connector, which effectively eliminates electromagnetic interference.
2. Description of the Related Art
When arranging electronic lines, transmission lines 71 are surrounded by an inner insulator 72 inside a tube of electrically conducting material 73 held in place by an outer insulator 70 (see FIG. 1A). Metal box and cable connector means are commonly used to connect cables of the aforesaid design. In order to eliminate electromagnetic interference and noises, a conducting member 600 is used (see FIG. 1B) is used with the cable connector. The conducting member 600 comprises a plurality of outwardly protruded stop portions 6003 formed of a part of the peripheral wall by stamping, a plurality of retaining arms 6001 respectively obliquely extended from the top end thereof toward the cable 70. The retaining arms 6001 each have a free end terminating in a curved contact portion 6002 disposed in contact with the tube of electrically conducting material 73 of the cable 70. During installation, the conducting member 600 is inserted into one end of the metal casing 100 of the cable connector, a flexible packing barrel 300 and a clamping ring 300 are inserted into the other end of the metal casing 100 (see FIG. 1), and then a packing nut 400 is threaded onto the metal casing 100 to compress the clamping ring 300 against the flexible packing barrel 300 and the cable 70. Further, a gasket ring 500 is fastened to the metal casing 100 to seal the gap between the metal casing 100 and the metal box (not shown) in which the cable connector is installed. This design of cable connector is still not satisfactory in function. The drawback of this design of cable connector is outlined hereinafter.
1. The conducting member 600 is complicated and expensive to manufacture, and the bulky design of the conducting member 600 requires much installation space. When in use, no means is provided to hold down the connection between the conducting member 600 and the metal casing 100, and a false contact between the conducting member 600 and the metal casing 100 results in poor EMI (electromagnetic interference) protection.
2. When pulling the cable 70 out of the connector for a replacement, the protruded stop portions 6003 and/or the retaining arms 6001 may be forced to break.
The present invention has been accomplished to provide an EMI protective cable connector, which eliminates the aforesaid problems. It is the main object of the present invention to provide an EMI protective cable connector, which effectively eliminates electromagnetic interference. It is another object of the present invention to provide an EMI protective cable connector, which is durable in use. According to one aspect of the present invention, the EMI protective cable connector comprises a metal casing fastened to a metal box by a gasket ring and a lock nut to hold a cable, a flexible packing barrel and a plastic clamping ring mounted in one end of the metal casing, a packing nut fastened to one end of the metal casing to compress the plastic clamping ring and the flexible packing barrel against the outer insulator of the cable, and a metal conducting plate stopped between a step inside the metal casing and one end of the flexible packing barrel and adapted for transmitting electromagnetic waves from the cable to the metal casing and then the metal box. The metal conducting plate comprises inwardly radially extended springy retaining arms, each springy retaining arm having a free end terminating in a curved contact portion disposed in contact with the tube of electrically conducting material of the cable. According to another aspect of the present invention, the curved contact portions of the springy retaining arms of the metal conducting plate are alternatively curved in reversed directions.